Method of manufacturing a tyre and apparatus for building a tyre

ABSTRACT

A bead wire loader device includes a shaft including two bearer elements. Each bearer elements includes a groove including a V-profile. A device for positioning tire bead wires on the building drum includes two support plates, a plurality of gripper units, and actuating devices for synchronous and uniform movement of the gripper units. The gripper units are arranged circumferentially around openings in the support plates and include at least one bead wire grasping element including a throat forming part of a single circumferential gripping profile common to the grasping elements. A tire building apparatus for a vehicle wheel includes a building drum and a bead wire placing system for fitting bead wires onto the building drum. The bead wire placing system includes the bead wire loader device and the device for positioning the bead wires. A related method of manufacturing a tire for a vehicle wheel is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national-phase entry under 35 U.S.C. § 371 fromInternational Application No. PCT/EP02/14615, filed Dec. 20, 2002, inthe European Patent Office, the content of which is relied upon andincorporated herein by reference; additionally, Applicants claim theright of priority under 35 U.S.C. § 119(a)-(d) based on patentapplication No. PCT/IT01/00655, filed Dec. 27, 2001, in the ItalianPatent Office.

BACKGROUND OF THE IINVENTION

1. Field of the Invention

The present invention relates in general terms to the placing of beadcores on a drum for building carcasses for tyres.

2. Description of the Related Art

A tyre generally comprises a carcass structure including at least acarcass ply, operatively associated with a pair of annular reinforcingstructures suitable for matching with a mounting rim, each annularreinforcing structure comprising at least a bead wire, and folded aroundthem, at least a belt structure at a radially external position withrespect to said at least a carcass ply, and a tread band at a radiallyexternal position with respect to the belt structure.

During the building of a tyre, a cylindrical carcass ply comprising oneor more reinforcing plies (containing cords embedded in a layer of anelastomeric material) is formed on a suitable drum. At least two beadcores are then positioned on this sleeve, coaxially with the axis ofrotation of the drum, which coincides with the axis of rotation of thetyre, in axially separated positions.

The cylindrical carcass ply constructed on the said drum will then beshaped into a torus, possibly after removal from the abovementioned drum(e.g. by contracting the drum).

The bead wire is a hoop of metal wires having different cross sections:for example, square, rectangular or hexagonal. The so-called Alderfertype has wires laid axially side by side and radially on top of eachother, and they are rubberized.

The twisted type has a basically round cross section, and the metalwires that form it are wound together around a central core. This typeof bead wire is typically not rubberized.

The process of assembling bead wires onto the carcass ply, by anautomatic or semi-automatic procedure, generally involves the followingsteps:

-   -   a) the bead wire is located on a device generally known as a        loader;    -   b) the bead wire is gripped by a device generally known as a        gripper;    -   c) the bead wire is positioned on the carcass ply.

Step a) can be done either manually by an operator or automatically.Either way, the bead wire can be made to swing when positioned on theloader device. It is important in this step for the bead wire to stopall swinging motion quickly and be stationary, and if possible alreadycoaxial with the building drum, when presented to the members of thegripper device, so that it can be gripped automatically, quickly andcorrectly.

The gripper device is often designed in such a way that its partsmaintain/position the bead wire coaxial with the drum axis, so that itcan be correctly and easily positioned on the carcass ply in step c).

An important requirement for bead wire placing systems relates to theflexibility of production changes. Bead wires come in a wide range ofdiameter measurements, depending on which type of tyre is being built.It is advantageous for economical and production reasons to find a beadwire placing system capable of controlling bead wires of differentdiameters with the minimum of replacements or adjustments of itsdevices.

Many tyre bead wire placing systems have been proposed. Many of thesegrasp the bead wire along its radially inner surface and/or employmagnetic means, in this case acting, for example, on its lateralsurface. In particular, this depends on the fact that the bead wires areoften loaded and positioned on the drum with their filler (a ring ofelastomeric material of circular or roughly triangular section) alreadyassembled on the radially outer surface of the bead wire.

For example, U.S. Pat. No. 5,051,149 (in the name of BridgestoneCorporation) describes, among other things, devices for loading,gripping and positioning bead wires to which the filler is alreadyassembled.

The said positioning device consists of a pair of support rings,attached to the inner surface of which is a plurality of radiallymoveable gripper devices. Each of the said gripper devices possesses,attached in a position corresponding to the portion facing the buildingdrum, a curved segment which itself comprises a plurality of magnetsembedded in its inner surface so as to grip a bead wire plus its filler.

In addition, each support ring is connected to a cylinder with a pistonwhose end portion is connected to the abovementioned gripper devices.When the said piston extends, all the gripper devices are movedsynchronously in a radially inward direction, and out again, by means ofa complex lever system.

The said loader device consists of two specular axially opposed unitsmounted on the outer end portions of the shaft that carries the buildingdrum. Each of the said units comprises mechanical gripper devices which,when moved radially outward, encounter the circumferentially innersurface of a bead wire supplied by an operator.

When the said loader devices come into relation with the correspondingpositioning devices, the magnets present in the latter capture the beadwire and hold it in exact alignment with the axis of the building drum.

The Applicant has noticed that the bead wire placing systems proposed inthe prior art are very complex, bulky and costly.

To be specific, the amount of radial space required by these knownsystems is linked with their ability to accept a wide range of bead wiremeasurements. This flexibility, which is desirable when it comes tochanging production, also affects the structure and disposition of thegripper units that must be adapted or even replaced when different beadwire measurements are required, and this obviously involves slowing downthe rate of production and, in the case of replacement, necessitatessomewhere to store the various parts.

Furthermore, producing a self-centring radial movement usually demands,as seen above, a complex system of gears and levers that weigh down theentire system and increase its cost.

SUMMARY OF THE INVENTION

The Applicant has found possible to simplify and at the same time toimprove the process for tyre building by reducing the radial spacerequirements of the bead wire placing system, and providing it withcharacteristics of flexibility and speed when it comes to productionchanges, while maintaining high levels of reliability of the system andof quality of the finished product, by loading the bead wire damping outany swinging movement that may have been given to it by the operator orby the automatic feeder system, gripping said bead wire by means ofgripper units that can be readily adapted to differing characteristicsof the product being built, and that are operated by a simple andflexible device for actuating the said units

In a first aspect, the present invention relates to a method ofmanufacturing a tyre for vehicle wheels, said tyre comprising a carcassstructure having at least a carcass ply operatively associated with apair of annular reinforcing structures suitable for matching with amounting rim, each annular reinforcing structure comprising at least abead wire, said at least one carcass ply being turned up at least on oneof said annular reinforcing structures, said method comprising the stepsof:

-   -   building a cylindrical carcass sleeve comprising said at least        one carcass ply and said pair of annular reinforcing structures,    -   applying a belt structure to said cylindrical carcass sleeve at        a radially external position,    -   applying a tread band to said belt structure at a radially        external position,    -   shaping said tyre into a toroidal conformation,    -   vulcanizing said tyre,    -   wherein said building step comprises at least the steps of:    -   feeding said at least a carcass ply onto a drum,    -   placing said annular reinforcing structure to a position        radially external to said carcass ply,    -   turning up said carcass ply on said annular reinforcing        structure,        wherein the step of placing said annular reinforcing structure        to a position radially external to said carcass ply comprises at        least the steps of:    -   locating said bead wire on a loader,    -   damping out any swinging on said bead wire,    -   gripping said bead wire by grasping elements,    -   positioning said bead wire on said at least one carcass ply.

Preferably, said step of gripping said bead wire is performed byoperating said grasping elements in a radial internal direction.

Preferably, said step of operating said grasping elements in a radialinternal direction is effected with a synchronous movement.

In a second aspect, the present invention relates to a tyre buildingapparatus for vehicle wheels including

-   -   a building drum, and    -   a bead wire placing system for fitting bead wires onto the said        building drum, provided with:        -   a device for loading the said bead wires, and        -   a device for positioning the said bead wires, comprising:            -   two support plates mutually moveable in both axial                directions, with respect to the said drum, each having                an opening whose cross section is not smaller than that                of the said drum;            -   a plurality of gripper units arranged circumferentially                on the said two support plates around the said opening                and operable radially in both directions with respect to                the axis of rotation of the said drum, and            -   actuating devices for synchronous and uniform movement                of the said gripper units,                wherein each of the said gripper units includes, at its                radially inward end, at least one grasping element for                the said bead wires that possesses, at least on the                radially inward surface, a throat lying in a plane                perpendicular to the said axis of rotation, forming part                of a single circumferential gripping profile common to                the said grasping elements, and said loader device                includes, parallel to the axis of the said drum, a shaft                supported cantilever-fashion near its axially outer end,                comprising two bearer element, one for each bead wire,                which bearer elements show, at least on their upper                surface, a groove lying in plane perpendicular to the                said axis of rotation, with a V profile in cross section                perpendicular to the said plane. The said shaft is                preferably moveable at least vertically in both                directions.

In the building apparatus according to the invention, the said one ormore grasping elements present on each of the said gripper units arepreferably fitted with devices for detecting correct positioning of thebead wire in the said throat. The said detector devices are preferablypin-type sensors, preferably connected to proximity detectors.

Also preferably, in the building apparatus according to the presentinvention, the said actuating devices include a flexible andinextensible element kinematically connected to the said gripper unitsand connected to a traction device.

In a preferred embodiment of the building apparatus of the invention,the said one or more grasping elements are suitably shaped discs.

The said disc-shaped grasping elements are preferably provided as a pairfor each gripper unit, wherein case the carrier arm to which the saiddiscs are connected is preferably shaped like a V whose apex is orientedin a radially outward direction.

The building apparatus of the invention preferably has at least eightgrasping elements.

The building apparatus of the invention preferably comprises gripperunits uniformly distributed around the said opening of the supportplate. They preferably comprise a bracket that has notches for adjustingthe position of each gripper unit with respect to the said supportplate.

The flexible and inextensible element forming part of the said actuatingdevices of the system of the invention may be for example a toothedbelt, preferably reinforced with wires embedded in an elastomericmaterial and laid generally parallel along the longitudinal direction ofthe belt.

The said flexible and inextensible element is preferably kinematicallyconnected to the said gripper units by a system of pulleys and clamps.

The said traction device preferably comprises a pneumatic cylinder,inside which a piston projecting from both bases of the said cylinderslides, and a stop element to control the end of stroke of one end ofthe said piston.

The bearer elements of the said loader device each preferably compriseat least two shaped wheels positioned in a carrier block connected tothe said shaft.

The said groove present in the said bearer element, in particular in thesaid wheels, have a V profile in cross section, preferably forming anangle of not less than 90°, preferably between about 100° and about 140°inclusive, more preferably about 120°.

In a second aspect, the present invention relates to a bead wire placingsystem for fitting tyre bead wires onto a building drum, comprising aloader device, a placing device and an actuating device as describedabove.

In a third aspect, the present invention relates to a bead wire loaderdevice, as described above, for supplying the said bead wires to anautomatic device for positioning bead wires on a tyre building drum.

In a fourth aspect, the present invention relates to a device forpositioning bead wires on a tyre building drum as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages will become clearer in the courseof detailed description of a preferred, but not exclusive, embodiment ofa tyre building apparatus according to the present invention. Thisdescription will be set out hereinbelow with reference to the attacheddrawings, which are provided purely as an indication and are thereforenot limiting. In the drawings:

FIG. 1 shows a general view, in side elevation, of a tyre buildingapparatus comprising a bead wire placing system according to the presentinvention;

FIG. 2 shows a front view of the positioning device of the inventionfacing the building drum;

FIG. 3 shows a detail, in front view facing the building drum, of asupport plate with gripper units, grasping elements and, partially, aflexible and inextensible element according to the present invention;

FIG. 4 shows a view in section taken on the line D-D as marked in FIG.3, of a gripper unit inclusive of grasping element, according to thepresent invention;

FIG. 5 shows a side view of the loader device according to theinvention;

FIGS. 6 and 7 show a front view on plane A-A and plane B-B,respectively, of FIG. 5, of bearer elements according to the invention;

FIGS. 8 a and 8 b show a detail of a bearer element according to theinvention in end view and side view, respectively;

FIG. 9 shows a front view facing the building drum of a grasping elementaccording to the present invention;

FIG. 10 shows a front view of a traction device according to the presentinvention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

A tyre generally comprises a carcass structure having at least a carcassply operatively associated with a pair of annular reinforcing structuressuitable for matching with a mounting rim, each annular reinforcingstructure comprising at least a bead wire, said at least one carcass plybeing turned up at least on one of said annular reinforcing structures,a belt structure at a radially external position with respect to said atleast a carcass ply, comprising at least a belt layer, and a tread bandat a radially external position with respect to said belt structure.

A method for manufacturing a tyre generally comprises the steps of:

-   -   building a cylindrical carcass sleeve comprising said at least        one carcass ply and said pair of annular reinforcing structures,        thus yielding said carcass structure;    -   applying said belt structure to said cylindrical carcass sleeve        at a radially external position,    -   applying said tread band to said belt structure at a radially        external position,    -   shaping said tyre into a toroidal conformation,    -   vulcanizing said tyre.

The method according to the invention further comprises the steps of:

-   -   feeding said at least a carcass ply onto a drum,    -   placing said annular reinforcing structures to a position        radially external to said carcass ply,    -   turning up said carcass ply on said annular reinforcing        structure.

FIG. 1 shows a general assembly, according to the present invention, ofa tyre building apparatus comprising a bead wire placing system. Thebuilding apparatus is illustrated in the pre-positioning step of thebead wires: two bead wires 9 have been located on bearer elements 14 a,14 b of a loader device 1. The bearer element 14 a is aligned, in aplane perpendicular to the axis of rotation C-C of the building drum 4(which is shown schematically in the drawing), with grasping element 8mounted on gripper units 6 present on a support plate 3 a belonging to apositioning device according to the invention. The said gripper units 6are shown radially retracted.

Another support plate 3 b is positioned on the far side of the buildingdrum 4.

In the rest of this description, the expression “axial direction” meansa direction parallel to the abovementioned axis C-C.

As an alternative, the said support plate 3 b may be situated on thesame side of the building drum 4 as the said support plate 3 a. Themovements in the axial direction of the said support plates 3 a, 3 band, where relevant, of the building drum 4 are mutual in bothdirections, and these units are moved, both independently andsynchronously, by at least one drive system—e.g. a belt drive.

FIG. 5 illustrates one embodiment of a loader device 1 according to thepresent invention. It has a shaft 13 projecting from a frame 17, andbearer elements 14 a, 14 b. The said frame 17 contains a first cylinder18 whose piston enables the shaft 13 to effect vertical movements inboth directions. The said first cylinder 18 may be of any type capableof performing the said function, e.g. operating by fluid or oil underpressure.

The bearer elements 14 a, 14 b each comprise, in the case illustrated inFIGS. 6 and 7, two shaped wheels 19. These lie in the same planeperpendicular to the axis of the said shaft 13 and are positioned in acarrier block 20 connected to the said shaft 13. The said shaped wheels19 are preferably not idle about their axis of rotation but insteadfixed firmly in the said carrier block 20.

In the particular case illustrated, the said bearer elements 14 a, 14 bare slightly offset in the vertical direction with respect to the axisof the shaft 13; in particular, the said wheels 19 of the said bearerelement 14 b are higher, in terms of the axis of the said shaft 13, thanthose of the said bearer element 14 a.

This specific arrangement becomes useful for placing bead wires fortyres having beads with two different diameters, as described forexample in patent application WO94/13498 (in the name of CompagnieGenerale des Etablissements Michelin—Michelin & CIE). Because of thedifferent diameters of the said beads, the bead wires used in this typeof tyre have different diameters; this characteristic is reflected inthe different vertical positioning, relative to the axis of the saidshaft 13, of the said bearer elements 14 a, 14 b, and in particular ofthe said shaped wheels 19, which will present the said bead wires to thepositioning device so as to be coaxial with each other.

The said shaped wheels 19 of the said bearer elements 14 a, 14 b have agroove 15 whose profile forms a V in the cross section of the planecontaining the axis of the said shaft 13, as shown in greater detail inFIGS. 8 a and 8 b. The V profile of the said groove 15 has an angle ofnot less than 90°, preferably between about 100° and about 140°inclusive, and more preferably equal to about 120°. The said V profile,particularly with the said angular values, has been found to be veryeffective at almost instantaneously damping out any swinging movementsimparted to the bead wire 9 by the operation of hanging the said beadwires on the said loader device 1. The result is surprising because thecross section of the bead wires is circular, which encouraged the ideathat for the said profiles, cross sections of complementary shape werethe best.

In alternative embodiments (not illustrated), a bearer element accordingto the invention may take the form of a block of suitable shape, e.g. aparallelepiped with at least one surface, in a vertically higherposition relative to the axis of the said shaft, that is suitably curvedand has a groove as described above.

The presence of shaped wheels 19 in the bearer devices 14 a, 14 b of theinvention is preferred. In time, the point on which the bead wires 9rest can become worn, and the fact that the said shaped wheels 19 can beturned to a new working position means that the whole of the surface ofthe said groove 15 can be used, thus greatly delaying the need toreplace the part.

The locating of the said bead wires 9 on the said bearer elements 14 a,14 b may be carried out either manually by an operator, or by suitableautomatic feeder mechanisms. As stated earlier, the special V form ofthe grooves 15 of the said bearer elements 14 a, 14 b virtuallyinstantaneously damps out any swinging movement that may have been givento the bead wires by the operator or by the automatic handlingmechanism. The said bead wires 9 are therefore motionless in their planewhen presented to the grasping elements 8.

After the said bead wires 9 are located on the respective bearerelements 14 a, 14 b, as diagrammatically illustrated in FIGS. 6 and 7,the said support plate 3 a is moved axially towards the said bearerdevices 14 a, 14 b until the grasping elements 8 are aligned with thesaid bearer element 14 a in the same plane perpendicular to the C-Caxis. Optionally, this alignment, and the reciprocal movements of thesupport plates 3 a, 3 b are governed by a suitable computer program.

Once the desired position is reached, gripper units 6, with the saidgrasping elements 8, are moved synchronously in an inward radialdirection relative to the C-C axis, by an actuating device.

FIGS. 2 and 3 show a complete and a partial frontal view, respectively,facing the building drum 4, of a support plate 3 belonging to thepositioning device of the invention.

In the case illustrated, the said gripper units 6 are arrangedcircumferentially and uniformly around an essentially circular opening 5in the said support plate 3. There are six such gripper units 6, andeach has one pair of grasping elements 8 in the form a shaped disc.There are preferably at least eight of the said grasping elements 8.

A V-shaped arm whose apex is oriented in a radially outward directionconnects the grasping elements 8 of the said pair. Schematically, thesaid gripper units 6 have a T shape with the longer dimension orientedin a radially outward direction, while the shorter dimension is formedby the said V-shaped arm which connects the said pair of graspingelements 8.

The said opening 5 is coaxial with the axis of rotation C-C of thebuilding drum 4.

Referring now to FIGS. 2, 3 and 4, an actuating device according to theinvention comprises a flexible and inextensible element 11, such as atoothed belt, possibly reinforced with wires laid generally parallelwith each other along the longitudinal direction of the said belt. Thesaid flexible and inextensible element 11 is situated on the axiallyoutward side of the support plate 3, that is the side hidden from thebuilding drum 4, and is kinematically connected to all the said gripperunits 6 of the said support plate 3 by a system of pairs of pulleys 16and clamps 7.

In FIG. 3 a “tensioner” 25 is visible. This is preferably a tensionadjusting roller and is useful for adjusting the length of the saidflexible and inextensible element 11 when setting up the device.

The said pulleys 16 are coupled in radial planes at shortcircumferential distances, one pulley close to the radially outer edgeand the other close to the radially inner edge of the said support plate3.

The said clamps 7 (visible in FIG. 4), of which there is preferably atleast one for each gripper unit 6, are connected to a bar 2 attached tothe long arm of the abovementioned T, hereinafter referred to as thebracket 22, which runs through the said support plate 3 via a slotextending in a radial direction in which the said bar 2 can move in bothdirections. The clamps 7 securely fasten the said gripper units 6, bymeans of the said bar 2, to the flexible and inextensible actuatingelement 11.

On the axially inward side of the support plate 3, that is the sidefacing the building drum 4, the said bracket 22 is appropriately fittedbetween two tracks (not clearly visible) by means of, for example, adovetail or other configuration suitable for vertical sliding of thesaid bracket 22.

In addition, in a preferred embodiment of the invention, the saidbracket 22 may have, on the side facing the support plate 3, notches 23for adapting the position of the gripper unit 6 to the particularmeasurement of the bead wire diameter. In particular, the said notchesdetermine the positions of the bar 2 and gripper unit 6 relative to eachother by coupling one of the said notches 23 with an index tooth 29integral with the said bar. Advantageously, markings at each of the saidnotches 23 may indicate the bead wire diameters.

The said flexible and inextensible element 11 is also connectedkinematically to a traction device 12 which can be seen in FIG. 10.

The said traction device 12 is preferably a linear-motion mechanism suchas, in the present case, a pneumatic cylinder 24, though it may beoperated by fluid or oil under pressure, inside which a piston 26projecting from both bases of the said cylinder slides. One end of thesaid piston 26 carries a clamp 30 to which the said flexible andinextensible element 11 is fastened. The said element 11 may be anendless loop, but preferably consists of a strip of suitable length withboth its ends locked in the said clamp.

The end-of-stroke position of the other end of the said second piston 26is controlled relative to the said support plate 3 by a stop element 27.

FIG. 10 represents the moment when the said second piston 26 has reachedthe upper end-of-stroke point: this position corresponds to the positionof maximum radial retraction of the said gripper units 6 (as illustratedfor example in FIGS. 2 and 3).

When the said piston 26 is lowered, the movement transmittedsynchronously and uniformly to the gripper units 6 by the said flexibleand inextensible element 11 moves the said gripper units 6 radiallyinwards towards said C-C axis, and makes the corresponding graspingelements 8 receive a bead wire 9.

The maximum radial advance of the gripper units 6 towards the said C-Caxis, i.e. the advance which sets the said grasping elements 8 to thediameter of the bead wire in question, is defined by a stop element 27which obstructs the movement of the said second piston 26 in thedescending direction. In a preferred embodiment of the invention, thesaid stop element 27 can be adjusted as a function of the diameter ofthe bead wire 9 to be accepted. Alternatively there may be a pluralityof interchangeable stop elements 27, each adapted to a different beadwire diameter.

As already explained, the synchronous and self-centring movement of thesaid gripper units 6 brings the corresponding grasping elements 8 intocontact with the bead wire 9. The radially outer surface (extrados) ofthe said bead wire fits into the throat 10 of the said grasping elements8.

In cross section, the throat 10 of the said grasping element 8, in theplane containing the said C-C axis, is a broken line resembling afunnel, as illustrated, for example, in FIG. 4.

FIG. 9 shows in greater detail a grasping element 8 in the form of ashaped disc. The said disc contains internally two channels 21 that arebasically perpendicular to each other.

The channel 21 whose axis is oriented essentially radially preferablycontains a detector device 28 (visible in FIG. 4) to see that the beadwire is correctly positioned in the throat 10 of the said graspingelement 8.

The said detector device 28 may be for example a pin-type sensor. Thepresence of the bead wire 9 in the said throat 10 pushes the saidpin-type sensor in a radially outward direction and, by acting on anelastic mechanism, such as a retaining spring, causes it to make anelectric contact which sends a signal to suitable proximity detectors.

In the same way as discussed with reference to the presence of shapedwheels 19 on the bearer devices 14 a, 14 b, the use of shaped discs forthe said grasping elements 8 of the invention is preferred because it ispossible to rotate its working position. In time, the point on which thebead wires rest on the said grasping element 8 can become worn, and theavailability of elements in the form of a shaped disc enables the wholesurface of the said throat 10 to be made use of, thereby considerablydelaying the time when the part requires replacing.

Alternatively, the said grasping element may be, for each gripper unit6, at least one block (not shown), preferably a pair, suitably shaped totake the extrados surface of the said bead wire 9.

In a similar way to the support plate 3 a, the said support plate 3 b ismoved in an axial direction to align the respective grasping elements 8with the said bearer element 14 b. The axial movement of the saidsupport plates 3 a, 3 b towards the said bearer elements 14 a, 14 bpreferably occurs in an essentially synchronous manner, although, forsimplicity of illustration, FIG. 1 shows a moment when the support plate3 a is already aligned with its bearer element 14 a, while support plate3 b is still waiting beyond the building drum 4.

Once the said bead wire 9 is in the throat 10 of the said graspingelements 8 of the support plates 3 a, 3 b, and its correct position hasbeen detected by the said detector device 28, the said loader device 1disengages with a vertical lowering movement of the said shaft 13, whichmovement is controlled by the said cylinder 18 enclosed in the saidframe 17 (as seen in FIG. 5).

In an alternative embodiment of the invention in which the said shaft isstatic, the translational movement of the bead wire from the bearerelements to the grasping elements takes place by means of a radialrelative movement of the elements, optionally facilitated by opposingspring means. The special shaping of the said groove and throatfacilitates this translational movement.

Following disengagement of the said loader device 1, the said supportplates 3 a, 3 b move axially towards the building drum 4.

In an alternative embodiment, it is either the said drum 4 that movesaxially towards the said plates, or both movements may coexist.

The relative positions taken up by the said support plates 3 a, 3 b withrespect to each other, and both with respect to the building drum 4, isadvantageously a function of the axial distance that it is wished tohave between the said bead wires 9 on the carcass ply during tyrebuilding.

Once the said support plates 3 a, 3 b have been appropriately positionedwith respect to the building drum 4, and the said bead wires have beenimmobilized on the said carcass ply, e.g. by radial expansion ofcorresponding portions of the said drum, the said traction device 12(FIG. 10) of each of the said support plates 3 a, 3 b is started. Inparticular, the said traction device 12 raises the said second piston 26to the end of its stroke; the said movement of the piston pulls the saidflexible and inextensible element 11 attached to the said second piston26, causing it to travel around the said pulleys 16.

Consequently, the said flexible and inextensible element 11 carries withitself the said clamps 7 (FIGS. 3 and 4), causing the gripper units 6 tomove synchronously and uniformly, radially away from the said opening 5.

This movement causes loss of contact between the said grasping elements8 and the said bead wires 9. The plates are now moved axially away fromthe said drum 4 to fetch two new bead wires that have been placed in themeantime on the said loader device 1.

As clearly explained in the above description, in the method accordingto the invention the step of placing said annular reinforcing structuresat radially external position over said carcass ply comprises at leastthe steps of:

-   -   locating said bead wire on a loader,    -   damping out any swinging on said bead wire,    -   gripping said bead wire by grasping elements,    -   positioning said bead wire on said at least one carcass ply.

In a preferred embodiment, as above set forth, said step of grippingsaid bead wire can be performed by operating said grasping elements in aradial internal direction.

Moreover, said step of operating said grasping elements in a radialinternal direction can be effected with a synchronous movement.

The present invention offers significant advantages.

The placing system forming part of the tyre building apparatus of thepresent invention takes up little radial space, is able to work with awide range of bead wire measurements, even including pairs of bead wiresof different diameters, and is economically advantageous both as regardsthe speed with which production can be changed, and because of theintrinsically low cost of the bead wire grasping and bearer elements.

The gripper units, the traction device and the actuating device of theinvention enable production to be changed quickly and withoutreplacement of parts. In particular, the position of the gripper unitson the bracket is adjusted by means of a male/female system(notch/tooth) which locks the said units in predetermined positions thatare easily identifiable by markings, one per notch, by means of aconnection device that allows the position of the said units on theirbracket to be varied simply by slackening a fixing screw on the bracket.

The stop element of the piston of the traction device is preferablyfitted with an adjustment mechanism for continuous adjustment of theposition of the grasping elements. The technician may alternatively usea plurality of quick-change stop elements, although the adjustment ofthe position of the grasping elements will then be discontinuous(discrete amounts).

The flexible and inextensible element forming part of the actuatingdevice is low cost and allows great flexibility in the construction ofthe system. Moreover, the said flexible and inextensible elementdispenses with the need for mechanical components in the self-centringradial-motion mechanism, which inevitably lead over time to mechanicalplay developing between connected parts. Such mechanical playcompromises the self-centring motion and the correct positioning of thebead wire. Added to this is the fact that the said flexible andinextensible element represents an excellent low-cost safety system, inas much as it can slide through the clamps, which comes into operationin the case of faults or wrong operations causing collision between thegrasping elements and the building drum.

As highlighted earlier, the use of structures such as shaped discs andwheels as points of contact between, respectively, the grasping andbearer elements and the bead wire, means that the same element can beused in several different positions. This greatly reduces the operatingcost. The said shaped discs and wheels may be made of plastic in orderto avoid damage to the building drum in the event of machine faults orwrong operations creating interference between the various mechanicalparts of the said devices.

1. A method of manufacturing a tyre for a vehicle wheel, comprising:building a cylindrical carcass sleeve; applying a belt structure to thecarcass sleeve at a position radially external to the carcass sleeve;applying a tread band to the belt structure at a position radiallyexternal to the belt structure; shaping the tyre into a toroidalconformation; and vulcanizing the tyre; wherein the tyre comprises: acarcass structure; the belt structure; and the tread band; wherein thecarcass structure comprises: at least one carcass ply; and a pair ofannular reinforcing structures; wherein the at least one carcass ply isoperatively associated with the annular reinforcing structures, whereinthe carcass sleeve comprises the at least one carcass ply and theannular reinforcing structures, wherein each annular reinforcingstructure comprises at least one bead wire, wherein the annularreinforcing structures are suitable for mounting the tyre on a rim,wherein the at least one carcass ply is turned up on at least one of theannular reinforcing structures, wherein building the carcass sleevecomprises: feeding the at least one carcass ply onto a drum; placing atleast one of the annular reinforcing structures at a position radiallyexternal to the at least one carcass ply; and turning up the at leastone carcass ply on the at least one of the annular reinforcingstructures; wherein placing at least one of the annular reinforcingstructures at a position radially external to the at least one carcassply comprises: locating the at least one bead wire by hanging the atleast one bead wire on a loader; damping out any swinging of the atleast one bead wire; gripping the at least one bead wire by graspingelements, the grasping elements comprising a plurality of shaped discs,including two shaped discs spaced circumferentially from one another ona radially inner end of a gripper unit support member, wherein grippingthe at least on bead wire by the grasping elements includes engaging thebead wire within a recess defined between portions of the shaped discs;and positioning the at least one bead wire on the at least one carcassply.
 2. The method of claim 1, wherein gripping the at least one beadwire is performed by operating the grasping elements in a radially innerdirection.
 3. The method of claim 2, wherein operating the graspingelements in a radially inner direction is effected with a synchronousmovement.
 4. An apparatus for building a tyre for a vehicle wheel,comprising: a building drum; and a bead wire placing system for fittingbead wires onto the building drum; wherein the bead wire placing systemcomprises: a device for loading the bead wires; and a device forpositioning the bead wires; wherein the loader device comprises a shaftparallel to an axis of rotation of the building drum, wherein the shaftis supported cantilever-fashion near an axially outer end of the shaft,wherein the shaft comprises two bearer elements, wherein each bearerelement comprises, at least on an upper surface of the bearer element, agroove lying in plane perpendicular to the axis of rotation of thebuilding drum, wherein the groove comprises a V-profile in across-section perpendicular to the plane, wherein the device forpositioning the bead wires comprises: two support plates; a plurality ofgripper units, the plurality of gripper units comprising a plurality ofgrasping elements; and actuating devices for synchronous and uniformmovement of the gripper units; wherein the support plates are mutuallymoveable in both axial directions with respect to the building drum,wherein each support plate comprises an opening comprising across-section not smaller than a cross-section of the building drum,wherein the gripper units are arranged circumferentially on the supportplates around the support plate openings, wherein the gripper unitsoperate radially in both directions with respect to the axis of rotationof the building drum, wherein the plurality of grasping elementscomprises, at a radially inner end of each gripper unit, two shapeddiscs spaced circumferentially from one another, wherein the two shapeddiscs comprise, at least on the radially inner surface, a throat lyingin a plane perpendicular to the axis of rotation of the building drum,and wherein the throat forms part of a single circumferential grippingprofile common to the grasping elements.
 5. The apparatus of claim 4,wherein the shaft is moveable at least vertically in both directions. 6.The apparatus of claim 4, wherein the actuating devices include aflexible and inextensible element kinematically connected to: thegripper units; and a traction device.
 7. The apparatus of claim 6,wherein the traction device comprises: a pneumatic cylinder; a piston;and a stop element.
 8. The apparatus of claim 6, wherein the flexibleand inextensible element is kinematically connected to the gripper unitsby a system of pulleys and clamps.
 9. The apparatus of claim 4, whereinat least one of the grasping elements is fitted with a device fordetecting a position of a respective bead wire in the throat.
 10. Theapparatus of claim 4, wherein the two shaped discs are connected by aV-shaped carrier arm, and wherein an apex of the V-shaped carrier arm isoriented in a radially outward direction.
 11. The building apparatus ofclaim 4, wherein the plurality of grasping elements comprises at leasteight grasping elements.
 12. The apparatus of claim 4, wherein thegripper units are uniformly distributed around the openings.
 13. Theapparatus of claim 4, wherein the groove comprises an angle greater thanor equal to 90°.
 14. The apparatus of claim 4, wherein the groovecomprises an angle greater than or equal to about 100° and less than orequal to about 140°.
 15. The apparatus of claim 4, wherein the groovecomprises an angle of about 120°.
 16. The apparatus of claim 4, whereinthe bearer elements each comprise at least two shaped wheels positionedin a carrier block connected to the shaft.
 17. The apparatus of claim 4,wherein the gripper units each comprise a bracket.
 18. The apparatus ofclaim 17, wherein the bracket comprises notches.
 19. A bead wire placingsystem for fitting a tyre bead wire onto a building drum, comprising: aloader device; a placing device; and an actuating device for synchronousand uniform movement of units having a plurality of shaped discs, eachunit comprising two of the shaped discs spaced circumferentially fromone another on a radially inner edge of the unit, for gripping the beadwire, wherein the plurality of shaped discs define a recess betweenportions of the shaped discs for receiving the bead wire.
 20. A beadwire loader device, comprising: a shaft parallel to an axis of rotationof a building drum; wherein the shaft is supported cantilever-fashionnear an axially outer end of the shaft, wherein the shaft comprises twobearer elements, wherein the bearer elements each comprise at least twoshaped wheels positioned in a carrier block connected to the shaft,wherein each bearer element comprises, at least on an upper surface ofthe bearer element, a groove lying in plane perpendicular to the axis ofrotation of the building drum, and wherein the groove comprises aV-profile in a cross-section perpendicular to the plane.
 21. A devicefor positioning tyre bead wires on a building drum, comprising: twosupport plates; a plurality of gripper units, the plurality of gripperunits comprising a plurality of grasping elements; and actuating devicesfor synchronous and uniform movement of the gripper units; wherein thesupport plates are mutually moveable in both axial directions withrespect to the building drum, wherein each support plate comprises anopening comprising a cross-section not smaller than a cross-section ofthe building drum, wherein the gripper units are arrangedcircumferentially on the support plates around the support plateopenings, wherein the gripper units operate radially in both directionswith respect to the axis of rotation of the building drum, wherein theplurality of grasping elements comprises, at a radially inner end ofeach gripper unit, two shaped discs spaced circumferentially from oneanother, wherein each of the shaped discs comprises, at least on aradially inner surface, a throat lying in a plane perpendicular to theaxis of rotation of the building drum, and wherein the throat forms partof a single circumferential gripping profile common to the graspingelements.